for those with Steel 72s...

[runsongas]

a hydrostatic facility conducting the visual can fail and condemn the tank during the pre hydro visual

 

[captain]

The only 72 explosive failures I am aware of took place in the 70's before yearly inspections became the norm and even then it was mostly out of the country where compressor and tank maintenance wasn't a high priority.

 

[rjack321]

I see the above as a bit of a deflection from the subject in question, but you and I (doing our jobs VIP'ing cylinders) keep this issue under control enough that our sport is very lightly federally regulated.

I have never taken money for a VIP. In the last 15 years I have done maybe 6 VIPs for other people. The rest were mine. I did fail a 72 once. I couldn't get the liner out tumbling. My hydro shop has a blasting wand they use to clean tanks with and whatever media they use has removed epoxy in the past so I sent it to them. They couldn't get 100% of it out either. But they did remove enough of it to expose very light pitting. I decided the tank wasnt worth trying to rehab at that point. The pits may have passed but the remnant epoxy looked like a rash in there and some of it was still in bad shape and lord knows what it might have been hiding.

 

[rjack321]

The only 72 explosive failures I am aware of took place in the 70's before yearly inspections became the norm and even then it was mostly out of the country where compressor and tank maintenance wasn't a high priority.

Not sure the boom date on the ones I have seen. Not recent that's for sure.

 

[rjack321]

Attached is the PST REE document-it may help.

Its so frustrating that the ONE line that is relevant has the typo on it. My hydro shop has given me the side eye on that form in the past. I dont really care, I just fill mine anyway.

 

[captain]

Rust causes paint to blister above it, you see it on cars. The same with tank epoxy coatings, if no blisters or flaking epoxy is present you can assume the underlying metal is rust free. Never had a shop refuse to test an epoxy lined tank.

 

[Bob DBF]

The pit limits for 72s are not reduced compared to other 3AA cylinders, but the wall thickness is less.

I would imagine this has to do with the service pressure of the tank.

 

[lowviz]

@captain,

You indirectly bring up something that I can't answer. Do you know if (or where to find out if) an epoxy-lined tank can be certified for nitrox or O2?

Fire Resistance of Plastics: Limiting Oxygen Index (LOI)

I never had to deal with one. We all know that the latest info is always on the web and VIP'ers damn well better be aware of it.

Best I have is this: https://apps.dtic.mil/dtic/tr/fulltext/u2/a135282.pdf

 

[2airishuman]

I use a local hydro shop that will + rate Norris and PST LP72s. I sold all my Kiddie LP72s because I can't get them + rated.

The LDSs around here fill by the book and so I get 2450. That's fine. If I want to dive longer I use an HP120.

 

[apenland01]

I use a local hydro shop that will + rate Norris and PST LP72s. I sold all my Kiddie LP72s because I can't get them + rated.

The LDSs around here fill by the book and so I get 2450. That's fine. If I want to dive longer I use an HP120.

Are you sure about Norris 72? I've not seen anything that documents what the hydro shop need to give a + rating on my Norris 72...